Underwater noise monitoring method for offshore wind plant

Abstract

The invention discloses an offshore wind plant underwater noise monitoring method, which comprises the following steps: equipment preparation and assembly: preparing an underwater noise monitoring unit for monitoring, the underwater noise monitoring unit being composed of a hydrophone, a rope, a buoy and a balancing weight; measuring an underwater noise background value: adopting one underwater noise monitoring unit to carry out underwater noise monitoring at a position which is in the upwind direction of the offshore wind power plant and is a certain distance away from the boundary of the site; influence range and attenuation characteristic measurement: respectively aiming at a single unit, two units and a plurality of units in the offshore wind power plant, adopting the underwater noise monitoring unit to carry out underwater noise monitoring; data collection and processing: recovering all the arranged underwater noise monitoring units, exporting monitoring data, analyzing and processing the monitoring data, and further quantitatively evaluating the influence range and attenuation law of underwater noise; according to the invention, systematicness, reliability and analyzability of underwater noise monitoring data in the operation period of the offshore wind plant are improved.

Description

Technical Field

[0001] This invention relates to the field of underwater noise monitoring technology, and in particular to a method for underwater noise monitoring of offshore wind farms. Background Technology

[0002] With the rapid development of my country's offshore wind power industry and the country's high regard for marine ecological civilization construction, the impact of underwater noise from offshore wind farms during operation on the surrounding environment has gradually become a focus of public attention and an urgent issue to be addressed in environmental impact studies. Underwater noise monitoring of offshore wind farms provides an important data foundation for environmental impact research. Current underwater noise monitoring technologies for offshore wind farms typically employ acoustic sensors such as hydrophones, deploying a limited number of monitoring points around the wind farm. These monitoring schemes lack systematicity, representativeness, and universality, and the results offer poor interpretation of underwater noise propagation characteristics and impact range, failing to meet the requirements for refined data analysis in environmental impact studies of underwater noise from offshore wind farms. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a method for underwater noise monitoring in offshore wind farms, thereby improving the systematicness, reliability, and analyzability of underwater noise monitoring data during the operation of offshore wind farms.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for underwater noise monitoring in offshore wind farms, comprising the following steps: Step 1: Equipment preparation and assembly: Prepare an underwater noise monitoring unit for monitoring, which consists of a hydrophone, rope, buoy and counterweight; Step 2: Underwater noise background measurement: Using one of the aforementioned underwater noise monitoring units, underwater noise monitoring is carried out at a location upwind of the offshore wind farm and at a certain distance from the site boundary; Step 3: Measurement of impact range and attenuation characteristics: Underwater noise monitoring is carried out using the underwater noise monitoring unit for single units, two units, and multiple units in offshore wind farms; Step 4: Data collection and processing: Retrieve all deployed underwater noise monitoring units and export the monitoring data. Analyze and process the monitoring data to quantitatively assess the impact range and attenuation pattern of underwater noise.

[0005] Preferably, in step 1, the specific operations for equipment preparation and assembly are as follows: the length of the rope is determined by increasing the actual water depth of the monitoring area by 10 meters; the counterweight is fixed to one end of the rope, and the total weight of the counterweight is 50 kg; the buoy is fixed at a position 20 m away from the other end of the rope; between the buoy and the counterweight, three hydrophones are fixed according to the three water layers of the surface, middle layer and bottom layer, respectively, to finally form the underwater noise monitoring unit.

[0006] Preferably, in step 2, underwater noise monitoring is carried out at a location 5 km away from the site boundary and upwind of the offshore wind farm; the monitoring time for the underwater noise background value is set to 10 minutes, and the underwater noise baseline data of the offshore wind farm when there is no turbine unit influence is obtained through the monitoring of this time.

[0007] Preferably, in step 3, the first operation process for underwater noise monitoring of a single unit is as follows: a single target wind turbine that is far away from other wind turbines is selected; an underwater noise monitoring unit is deployed at different locations and distances around the target wind turbine, for a total of 16 underwater noise monitoring units; the single monitoring time of each underwater noise monitoring unit is 10 minutes, in order to obtain underwater noise distribution data around the single unit.

[0008] Preferably, in step 3, the second operation process for underwater noise monitoring of a single unit is as follows: along the direction away from the offshore wind field, starting from the target single wind turbine, one underwater noise monitoring unit is deployed every 100m, for a total of 10 underwater noise monitoring units; the single monitoring time of each underwater noise monitoring unit is 10min, in order to obtain the attenuation law data of the underwater noise of the single unit.

[0009] Preferably, in step 3, the specific operation for underwater noise monitoring of the two units is as follows: two adjacent target wind turbines are selected; an underwater noise monitoring unit is deployed every 100m along the line connecting the two target wind turbines; the single monitoring time of each underwater noise monitoring unit is 10min, so as to obtain underwater noise change data under the superposition of noise from the two units.

[0010] Preferably, in step 3, the specific operation for underwater noise monitoring of multiple units is as follows: multiple target wind turbines are regarded as a surface sound source; the midpoint of the line connecting the multiple target wind turbines is determined, and an underwater noise monitoring unit is deployed every 100m along a direction perpendicular to the midpoint and facing downwind of the wind field; the single monitoring time of each underwater noise monitoring unit is 10min, so as to obtain the overall underwater noise impact data of multiple units.

[0011] Preferably, in step 4, the specific data processing operations are as follows: frequency domain analysis and time domain analysis are performed on the exported monitoring data using professional acoustic analysis software; based on the analysis results, three core parameters—sound pressure level, spectral characteristics, and propagation loss—are calculated; underwater noise contour maps are drawn by combining the actual spatial deployment locations of all the underwater noise monitoring units; and the influence range and attenuation law of underwater noise are quantitatively assessed based on the noise contour maps and core parameters.

[0012] Preferably, in step 1, the placement positions of the three hydrophones correspond to the surface water layer, the middle water layer, and the bottom water layer between the buoy and the counterweight, respectively, and the three hydrophones are activated simultaneously to achieve synchronous acquisition of underwater noise at different water layers at the same monitoring point.

[0013] Preferably, in step 3, underwater noise monitoring for single units, two units, and multiple units is carried out by using three hydrophones in the underwater noise monitoring unit to simultaneously acquire underwater noise data from the surface, middle, and bottom water layers, thereby achieving synchronous monitoring of multiple water layers under different unit scenarios.

[0014] Preferably, in step 3, the 16 underwater noise monitoring units deployed around a single unit are distributed in multiple directions, including 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, and in different distance levels, such as 100m and 300m, to fully cover the noise impact area of ​​the single unit.

[0015] Preferably, the rope is a corrosion-resistant composite rope with a built-in steel wire skeleton, and five tension sensors are spaced apart along the length of the rope. During the monitoring process, if any tension sensor detects a tension fluctuation exceeding the threshold, it indicates that the water flow impact has caused the rope to be pulled. The rope length is then adjusted by the miniature retraction mechanism mounted on the buoy to ensure that the deployment depth deviation of the three hydrophones is always ≤1m.

[0016] Preferably, the monitoring unit in the direction of the connection between the two units also needs to synchronously collect real-time operating data (including blade speed and nacelle power) of the two units; during data processing, the unit operating data is correlated with the corresponding underwater noise data, and the noise data during the period of "stable blade speed and stable power" is selected to evaluate the actual superimposed noise of the two units.

[0017] Preferably, in step 3, the deployment of all monitoring units is first carried out by constructing a numerical model of "water flow-noise propagation" of the monitoring area using numerical simulation software. Based on the model prediction, the monitoring units are deployed densely in areas with high noise sensitivity and sparsely in areas with low noise sensitivity.

[0018] Preferably, the deployment of all monitoring units in step 3 is performed according to the following logic: 1) Constructing a coupled numerical model of "water flow-noise propagation": Using numerical simulation software, a numerical model of "water flow-noise propagation" for the monitoring area is established by incorporating water flow convection effects and marine environment correction terms into the steady-state acoustic wave equation (Helmholtz equation). The core expression of the model is: ; Where: p is the underwater noise sound pressure; ρ is the seawater density; c is the seawater sound speed; α is the water flow velocity vector; α is the marine environment attenuation coefficient; Q is the wind turbine noise source intensity; For gradient operators, For time partial derivatives; 2) Sensitive area definition and site selection: The spatial distribution of noise sound pressure level is obtained by solving the model. Areas with sound pressure levels significantly higher than the background value and that may affect marine life are identified as high-sensitivity areas, while areas with sound pressure levels close to the background value are identified as low-sensitivity areas. Monitoring units are deployed in high-sensitivity areas with denser spacing and in low-sensitivity areas with sparse spacing, with the spacing adapted to the noise attenuation gradient predicted by the model. 3) Environmental adaptation adjustment: When setting up the monitoring points, the boundary of the sensitive area predicted by the model is fine-tuned based on the actual water flow velocity and seabed roughness data of the monitoring area to ensure that the point setting conforms to the noise propagation law and is adapted to the on-site marine environmental conditions.

[0019] Beneficial effects of this invention: 1. This invention, through systematic point deployment and multi-level synchronous monitoring, can accurately reflect the spatial distribution and attenuation characteristics of underwater noise, significantly improving the systematicness, reliability and analyzability of monitoring data, and providing a scientific basis for environmental impact research.

[0020] 2. The monitoring method of the present invention is applicable to offshore wind farms in different regions and with different layouts, and has a certain degree of universality. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating a method for underwater noise monitoring in offshore wind farms. Figure 2 Schematic diagram of underwater noise monitoring unit; Figure 3 A top-down schematic diagram showing the layout of monitoring points for the underwater noise impact range of a single generating unit; Figure 4 A frontal view of the layout of monitoring points for the underwater noise impact range of a single generating unit; Figure 5 A layout diagram of monitoring points for the combined underwater noise impact of the two generating units; Figure 6A map showing the layout of monitoring points for the underwater noise impact range of multiple generating units. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0023] Example 1: As Figure 1 As shown, a method for underwater noise monitoring in offshore wind farms includes the following steps: Step 1: Equipment preparation and assembly: Prepare an underwater noise monitoring unit for monitoring, which consists of a hydrophone, rope, buoy and counterweight; Step 2: Underwater noise background measurement: Using one of the aforementioned underwater noise monitoring units, underwater noise monitoring is carried out at a location 5 km away from the site boundary and upwind of the offshore wind farm; Step 3: Measurement of impact range and attenuation characteristics: Underwater noise monitoring is carried out using the underwater noise monitoring unit for single units, two units, and multiple units in offshore wind farms; Step 4: Data collection and processing: Retrieve all deployed underwater noise monitoring units and export the monitoring data. Analyze and process the monitoring data to quantitatively assess the impact range and attenuation pattern of underwater noise.

[0024] Preferably, in step 1, the specific operations for equipment preparation and assembly are as follows: the length of the rope is determined by increasing the actual water depth of the monitoring area by 10 meters; the counterweight is fixed to one end of the rope, and the total weight of the counterweight is 50 kg; the buoy is fixed at a position 20 m away from the other end of the rope; between the buoy and the counterweight, three hydrophones are fixed according to the three water layers of the surface, middle layer and bottom layer, respectively, to finally form the underwater noise monitoring unit.

[0025] Preferably, in step 2, the monitoring time for the underwater noise background value is set to 10 minutes, and the underwater noise baseline data of the offshore wind farm when there is no generator unit is obtained through monitoring for this duration.

[0026] Preferably, in step 3, the first operation process for underwater noise monitoring of a single unit is as follows: a single target wind turbine that is far away from other wind turbines is selected; an underwater noise monitoring unit is deployed at different locations and distances around the target wind turbine, for a total of 16 underwater noise monitoring units; the single monitoring time of each underwater noise monitoring unit is 10 minutes, in order to obtain underwater noise distribution data around the single unit.

[0027] Preferably, in step 3, the second operation process for underwater noise monitoring of a single unit is as follows: along the direction away from the offshore wind field, starting from the target single wind turbine, one underwater noise monitoring unit is deployed every 100m, for a total of 10 underwater noise monitoring units; the single monitoring time of each underwater noise monitoring unit is 10min, in order to obtain the attenuation law data of the underwater noise of the single unit.

[0028] Preferably, in step 3, the specific operation for underwater noise monitoring of the two units is as follows: two adjacent target wind turbines are selected; an underwater noise monitoring unit is deployed every 100m along the line connecting the two target wind turbines; the single monitoring time of each underwater noise monitoring unit is 10min, so as to obtain underwater noise change data under the superposition of noise from the two units.

[0029] Preferably, in step 3, the specific operation for underwater noise monitoring of multiple units is as follows: multiple target wind turbines are regarded as a surface sound source; the midpoint of the line connecting the multiple target wind turbines is determined, and an underwater noise monitoring unit is deployed every 100m along a direction perpendicular to the midpoint and facing downwind of the wind field; the single monitoring time of each underwater noise monitoring unit is 10min, so as to obtain the overall underwater noise impact data of multiple units.

[0030] Preferably, in step 4, the specific data processing operations are as follows: frequency domain analysis and time domain analysis are performed on the exported monitoring data using professional acoustic analysis software; based on the analysis results, three core parameters—sound pressure level, spectral characteristics, and propagation loss—are calculated; underwater noise contour maps are drawn by combining the actual spatial deployment locations of all the underwater noise monitoring units; and the influence range and attenuation law of underwater noise are quantitatively assessed based on the noise contour maps and core parameters.

[0031] Preferably, in step 1, the placement positions of the three hydrophones correspond to the surface water layer, the middle water layer, and the bottom water layer between the buoy and the counterweight, respectively, and the three hydrophones are activated simultaneously to achieve synchronous acquisition of underwater noise at different water layers at the same monitoring point.

[0032] Preferably, in step 3, underwater noise monitoring for single units, two units, and multiple units is carried out by using three hydrophones in the underwater noise monitoring unit to simultaneously acquire underwater noise data from the surface, middle, and bottom water layers, thereby achieving synchronous monitoring of multiple water layers under different unit scenarios.

[0033] Preferably, in step 3, the 16 underwater noise monitoring units deployed around a single unit are distributed in multiple directions, including 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, and in different distance levels, such as 100m and 300m, to fully cover the noise impact area of ​​the single unit.

[0034] Preferably, the rope is a corrosion-resistant composite rope with an internal steel wire skeleton, and five tension sensors are spaced apart along its length. During monitoring, if any tension sensor detects a tension fluctuation exceeding a threshold, indicating that water flow impact is causing rope tension, the rope length is adjusted via a miniature deployment and retraction mechanism mounted on the buoy to ensure that the deployment depth deviation of the three hydrophones is always ≤1m. This design solves the problem that a fixed rope length cannot adapt to sea tides and that water flow causes hydrophone depth deviation and data distortion. Preferably, the monitoring unit along the connection direction of the two units also needs to synchronously collect real-time operating data (including blade speed and nacelle power) of the two units. During data processing, the unit operating data is correlated with the corresponding underwater noise data to filter out noise data during periods of "stable blade speed (fluctuation ≤ 2 rpm) and stable power (fluctuation ≤ 5%)", which is used to assess the actual superimposed noise of the two units. This design, through "operating data-noise data linkage filtering", eliminates interference from unstable operating conditions and represents a refined optimization for the operating characteristics of the wind turbine.

[0035] Preferably, in step 3, the deployment of all monitoring units is first based on the construction of a numerical model of the "water flow-noise propagation" of the monitoring area using numerical simulation software. Based on the model's predictions, monitoring units are deployed more densely in high-noise-sensitive areas and less densely in low-noise-sensitive areas. This solution optimizes the allocation of monitoring resources through "numerical simulation prediction + on-demand density / sparse deployment," and the combination of "numerical simulation and on-site deployment" enables intelligent deployment optimization, improving monitoring efficiency and data relevance.

[0036] Preferably, the deployment of all monitoring units in step 3 is performed according to the following logic: 1) Constructing a coupled numerical model of "water flow-noise propagation": Using numerical simulation software, a numerical model of "water flow-noise propagation" for the monitoring area is established by incorporating water flow convection effects and marine environment correction terms into the steady-state acoustic wave equation (Helmholtz equation). The core expression of the model is: ; Where: p is the underwater noise sound pressure; ρ is the seawater density; c is the seawater sound speed; α is the water flow velocity vector; α is the marine environment attenuation coefficient; Q is the wind turbine noise source intensity; For gradient operators, For time partial derivatives; 2) Sensitive Area Delineation and Monitoring Unit Placement: The spatial distribution of noise sound pressure level is obtained through model solving. Areas with sound pressure levels significantly higher than the background value and potentially affecting marine life are identified as high-sensitivity areas (noise sound pressure level ≥ 110 dB), while areas with sound pressure levels close to the background value are identified as low-sensitivity areas (noise sound pressure level ≤ 80 dB). Monitoring units are placed at a denser spacing (50 m) in high-sensitivity areas and at a sparser spacing (200 m) in low-sensitivity areas, with the spacing adapted to the noise attenuation gradient predicted by the model. 3) Environmental adaptation adjustment: When setting up the monitoring points, the boundary of the sensitive area predicted by the model is fine-tuned based on the actual water flow velocity and seabed roughness data of the monitoring area to ensure that the point setting conforms to the noise propagation law and is adapted to the on-site marine environmental conditions.

[0037] Example 2: An underwater noise monitoring method for offshore wind farms. This method uses multiple hydrophones to conduct simultaneous underwater noise monitoring at different water levels, directions, and distances for single units, two units, and multiple units, significantly improving the systematicness, reliability, and analyzability of underwater noise monitoring data during the operation of offshore wind farms.

[0038] The above objectives can be achieved through the following approach: (1) Equipment preparation and assembly The equipment required for underwater noise monitoring in offshore wind farms includes hydrophones, ropes, buoys, and counterweights. The rope length is determined by increasing the water depth by 10 meters based on the monitoring area. A counterweight (total weight 50 kg) is fixed to one end of the rope, and a buoy is fixed 20 m from the other end of the rope. Three hydrophones are fixed between the buoy and the counterweight, one for the surface, one for the middle layer, and one for the bottom layer. This constitutes one underwater noise monitoring unit. (See attached diagram) Figure 2 ).

[0039] (2) Measurement of underwater noise background value Using an underwater noise monitoring unit, underwater noise monitoring was conducted at a location 5 km upwind of the offshore wind farm site boundary for 10 minutes.

[0040] (3) Measurement of influence range and attenuation characteristics 1) Single unit Underwater noise monitoring for a single unit needs to be carried out on a single wind turbine that is far away from other wind turbines.

[0041] Sixteen underwater monitoring units were deployed at different locations and distances around the wind turbine, as detailed in the appendix. Figure 3 Monitoring time: 10 minutes.

[0042] Underwater noise attenuation monitoring was conducted by deploying one underwater noise monitoring unit every 100 meters from the wind turbine in a direction away from the wind farm, for a total of 10 units. See the appendix for details. Figure 4 Monitoring time: 10 minutes.

[0043] 2) Two generating units Select two nearby wind turbines and deploy an underwater noise monitoring unit every 100 meters along the line connecting the two turbines. See the appendix for details. Figure 5 The monitoring time is 10 minutes. The monitoring focuses on the changes in underwater noise under the combined influence of two wind turbines.

[0044] 3) Multiple generating units Treating multiple wind turbines as area noise sources, an underwater noise monitoring unit is deployed every 100 meters along the downwind direction, perpendicular to the midpoint of the line connecting the turbines. (See details...) Figure 6 The monitoring time is 10 minutes.

[0045] (4) Data collection and processing Retrieve all underwater noise monitoring units and export the monitoring data. Perform frequency and time domain analysis using professional acoustic analysis software to calculate parameters such as sound pressure level, spectral characteristics, and propagation loss. Combined with the spatial distribution of each monitoring point, draw noise contour maps to quantitatively assess the noise impact range and attenuation pattern.

[0046] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A method for underwater noise monitoring in offshore wind farms, characterized in that, Includes the following steps: Step 1: Equipment preparation and assembly: Prepare an underwater noise monitoring unit for monitoring, which consists of a hydrophone, rope, buoy and counterweight; Step 2: Underwater noise background measurement: Using one of the aforementioned underwater noise monitoring units, underwater noise monitoring is carried out at a location upwind of the offshore wind farm and at a certain distance from the site boundary; Step 3: Measurement of impact range and attenuation characteristics: Underwater noise monitoring is carried out using the underwater noise monitoring unit for single units, two units, and multiple units in offshore wind farms; Step 4: Data collection and processing: Retrieve all deployed underwater noise monitoring units and export the monitoring data. Analyze and process the monitoring data to quantitatively assess the impact range and attenuation pattern of underwater noise.

2. The underwater noise monitoring method for offshore wind farms according to claim 1, characterized in that, In step 1, the specific operations for equipment preparation and assembly are as follows: the length of the rope is determined by increasing the actual water depth of the monitoring area by 10 meters; the counterweight is fixed to one end of the rope, and the total weight of the counterweight is 50 kg; the buoy is fixed at a position 20 m away from the other end of the rope; between the buoy and the counterweight, three hydrophones are fixed according to the three water layers of the surface, middle layer and bottom layer, respectively, to finally form the underwater noise monitoring unit.

3. The underwater noise monitoring method for offshore wind farms according to claim 1, characterized in that, In step 2, underwater noise monitoring is carried out at a location 5 km away from the site boundary and upwind of the offshore wind farm. The monitoring time for the underwater noise background value is set to 10 minutes, and the underwater noise baseline data when there is no turbine influence at the offshore wind farm is obtained through this monitoring time.

4. The method for underwater noise monitoring of offshore wind farms according to claim 1, characterized in that, In step 3, the first operation for underwater noise monitoring of a single unit is as follows: a single target wind turbine that is far away from other wind turbines is selected; an underwater noise monitoring unit is set up at different locations and distances around the target wind turbine, for a total of 16 underwater noise monitoring units; the single monitoring time of each underwater noise monitoring unit is 10 minutes, in order to obtain underwater noise distribution data around the single unit.

5. The method for underwater noise monitoring of offshore wind farms according to claim 4, characterized in that, In step 3, the second operation for underwater noise monitoring of a single unit is as follows: along the direction away from the offshore wind field, starting from the target single wind turbine, one underwater noise monitoring unit is deployed every 100m, for a total of 10 underwater noise monitoring units; the single monitoring time of each underwater noise monitoring unit is 10min, in order to obtain the attenuation law data of the underwater noise of the single unit.

6. The underwater noise monitoring method for offshore wind farms according to claim 1, characterized in that, In step 3, the specific operation for underwater noise monitoring of the two units is as follows: two adjacent target wind turbines are selected; an underwater noise monitoring unit is deployed every 100m along the line connecting the two target wind turbines; the single monitoring time of each underwater noise monitoring unit is 10min, in order to obtain underwater noise change data under the superposition of noise from the two units.

7. The method for underwater noise monitoring of offshore wind farms according to claim 1, characterized in that, In step 3, the specific operation for underwater noise monitoring of multiple units is as follows: multiple target wind turbines are regarded as a surface sound source; the midpoint of the line connecting the multiple target wind turbines is determined, and an underwater noise monitoring unit is deployed every 100m along a direction perpendicular to the midpoint and facing downwind of the wind field; the single monitoring time of each underwater noise monitoring unit is 10min, so as to obtain the overall underwater noise impact data of multiple units.

8. The method for underwater noise monitoring of offshore wind farms according to claim 1, characterized in that, In step 4, the specific data processing operations are as follows: frequency domain analysis and time domain analysis are performed on the exported monitoring data using professional acoustic analysis software; based on the analysis results, three core parameters—sound pressure level, spectral characteristics, and propagation loss—are calculated; underwater noise contour maps are drawn by combining the actual spatial deployment locations of all the underwater noise monitoring units; and the influence range and attenuation law of underwater noise are quantitatively assessed based on the noise contour maps and core parameters.

9. The underwater noise monitoring method for offshore wind farms according to claim 2, characterized in that, In step 1, the three hydrophones are positioned at locations corresponding to the surface water layer, middle water layer, and bottom water layer between the buoy and the counterweight, respectively. The three hydrophones are activated simultaneously to collect underwater noise from different water layers at the same monitoring point.

10. The method for underwater noise monitoring of offshore wind farms according to claim 1, characterized in that, In step 3, underwater noise monitoring for single units, two units, and multiple units is carried out by using three hydrophones in the underwater noise monitoring unit to simultaneously acquire underwater noise data from the surface, middle, and bottom water layers, thereby achieving synchronous monitoring of multiple water layers under different unit scenarios.

11. The method for underwater noise monitoring of offshore wind farms according to claim 4, characterized in that, In step 3, the 16 underwater noise monitoring units deployed around a single unit are distributed in multiple directions, including 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315°, and in different distance levels, such as 100m and 300m, to fully cover the noise impact area of ​​the single unit.

12. The method for underwater noise monitoring of offshore wind farms according to claim 2, characterized in that, The rope is a corrosion-resistant composite rope with an internal steel wire skeleton, and five tension sensors are spaced apart along the length of the rope. During the monitoring process, if any tension sensor detects a tension fluctuation exceeding the threshold, it indicates that the water flow impact is causing the rope to be pulled. The rope length is then adjusted by the miniature retraction mechanism mounted on the buoy to ensure that the deployment depth deviation of the three hydrophones is always ≤1m.

13. The method for underwater noise monitoring of offshore wind farms according to claim 6, characterized in that, The monitoring unit along the line connecting the two units also needs to simultaneously collect real-time operating data (including blade speed and nacelle power) of the two units. During data processing, the unit operating data is correlated with the corresponding underwater noise data to filter out the noise data during the period when "blade speed and power are stable" for evaluating the actual superimposed noise of the two units.

14. The method for underwater noise monitoring of offshore wind farms according to claim 1, characterized in that, In step 3, the deployment of all monitoring units is first carried out by constructing a numerical model of "water flow-noise propagation" in the monitoring area using numerical simulation software. Based on the model prediction, the monitoring units are deployed densely in areas with high noise sensitivity and sparsely in areas with low noise sensitivity.

15. The method for underwater noise monitoring of offshore wind farms according to claim 14, characterized in that, The deployment of all monitoring units in step 3 is performed according to the following logic: 1) Constructing a coupled numerical model of "water flow-noise propagation": Using numerical simulation software, a numerical model of "water flow-noise propagation" for the monitoring area is established by incorporating water flow convection effects and marine environment correction terms into the steady-state acoustic wave equation (Helmholtz equation). The core expression of the model is: ； Where: p is the underwater noise sound pressure; ρ is the seawater density; c is the seawater sound speed; α is the water flow velocity vector; α is the marine environment attenuation coefficient; Q is the wind turbine noise source intensity; For gradient operators, For time partial derivatives; 2) Sensitive area definition and site selection: The spatial distribution of noise sound pressure level is obtained by solving the model. Areas with sound pressure levels significantly higher than the background value and that may affect marine life are identified as high-sensitivity areas, while areas with sound pressure levels close to the background value are identified as low-sensitivity areas. Monitoring units are deployed in high-sensitivity areas with denser spacing and in low-sensitivity areas with sparse spacing, with the spacing adapted to the noise attenuation gradient predicted by the model. 3) Environmental adaptation adjustment: When setting up the monitoring points, the boundary of the sensitive area predicted by the model is fine-tuned based on the actual water flow velocity and seabed roughness data of the monitoring area to ensure that the point setting conforms to the noise propagation law and is adapted to the on-site marine environmental conditions.

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